Realm Names

Realm names can consist of any ASCII string. Usually, the realm name
is the same as your DNS domain name, except that the realm name is in uppercase.
This convention helps differentiate problems with the Kerberos service from
problems with the DNS namespace, while using a name that is familiar. If you
do not use DNS or you choose to use a different string, then you can use any
string. However, the configuration process requires more work. The use of
realm names that follow the standard Internet naming structure is wise.